Thompson, who struggled to maintain her composure as she talked about her little girl, said she has been told little about the police investigation, just that authorities are searching a vacant house 500 yards from where the Florida second-grader was last seen.

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"My main thing is I want this guy caught," she said. "I want them to find him."

Somer disappeared Monday afternoon while walking home from school with her twin brother and older sister, 10. She ran ahead after a squabble with her siblings and vanished shortly after.

Somer's body was found Wednesday in a Georgia landfill after detectives followed garbage trucks from Somer's Orange Park, Fla., hometown in search of clues.

A preliminary autopsy has been completed, but Clay County Sheriff spokeswoman Mary Justino declined to provide details Thursday on the cause of death or the condition of the body.

Thompson said today that she has been wracked by feelings of guilt and responsibility for being at work when her youngest daughter disappeared.

"I feel responsible," she said. " If I could have just, I don't know, left work or something and been able to pick her up, this wouldn't have happened."

And her surviving children are also struggling. Thompson said she's afraid to let them out of her sight, lest it happen again. They will be getting counseling after Somer's funeral, she said.

"They go through spurts, you know, they're kids," she said. "One minute they're happy, and the next minute they're sad."

Sheriff: 'I Fear for Our Community'

Police have worked their way through many of the 651 leads called into the tip line, with another 231 leads still to be assigned to the more than 50 law enforcement officials working the case around the clock.